We live in an over-networked world where security becomes more and more important to protect us from information thefts, servers downtimes and other attacks.
Various solutions exist. I have recently given an internal presentation to present Prelude SIM (Security Information Management) System, a project I have contributed to. It's an OpenSource solution which allows you to monitor in real-time your infrastructure by correlating events from deployed sensors such as Snort (IDS), Samhain (FileSystem Integrity Checker) or Prelude-LML (Log analyzer) and helps you react quickly to a potential attack.
Here are my slides : Prelude SIM Talk